The corneal endothelium is being studied to further understand morphological changes as they relate to biological changes. In vitro experiments using a variety of toxic substances have been used to produce morphological changes in corneal thickness as observed and measured by the Maurice specular microscope. These changes are correlated with ultrastructural changes. Inhibitions of biological functions have been studied by autoradiographic techniques. Future techniques of tissue culture should allow further assessment of the biological function as related to observable changes. Technical advances observing the endothelial cell and assessing its funtional capacity are under investigation. Techniques of scanning photography (Maurice), stereo photography, and time lapse cinematography are used. Newer, more efficient techniques in corneal thickness measurement in vitro are being sought for better experimental control. Eventually more sensitive methods of recording corneal changes are sought. These areas of research relate to the overall goal - development of a means to assess endothelial function and its potential for survival under stressed conditions such as surgery, infection, preservation and exposure to substances from intraocular injection.